Bhopal tragedy occurred due to a highly toxic chemical:

The Bhopal gas tragedy occurred on the night of December 2–3, 1984, at the Union Carbide India Limited pesticide plant in Bhopal, Madhya Pradesh. The disaster was caused by the accidental leakage of highly toxic Methyl Isocyanate (${\text{CH}}_3\text{NCO}$) gas, leading to thousands of immediate fatalities and long-term health consequences for the exposed population.